IMPROVED NIST WIDEBAND SAMPLING VOLTMETER TO CHARACTERIZE FAST PULSES.The NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. wideband sampling voltmeter is a precision equivalent-time waveform The shape of a signal. See wavelength, sine wave and square wave. digitizing instrument for making accurate measurements of repetitive signals ranging in frequency from 10 Hz to 200 MHz (MegaHertZ) One million cycles per second. It is used to measure the transmission speed of electronic devices, including channels, buses and the computer's internal clock. A one-megahertz clock (1 MHz) means some number of bits (16, 32, 64, etc. . A previous version is used to determine the settling characteristics of fast pulse generators Pulse generator An electronic circuit capable of producing a waveform that rises abruptly, maintains a relatively flat top for an extremely short interval, and then rapidly falls to zero. but is not capable of characterizing their transition- duration (i.e., rise-time). When designing and testing high-speed circuits, such as those using i GHz microprocessors, one of the most difficult tasks is to verify that the high-speed signals all arrive consistently at the proper time. An accurate measurement of pulse transition- duration is crucial to verifying such circuit operation. An improved , gated- oscillator oscillator Mechanical or electronic device that produces a back-and-forth periodic motion. A pendulum is a simple mechanical oscillator that swings with a constant amplitude, requiring the addition of energy at each swing only to compensate for the energy lost because of air type of time-base has now been developed for the voltmeter that overcomes the limitations of the earlier design. Besides having an impressive basic performance, its timing linearity is improved even further with the use of a unique built-in hardware correction circuit and auto-calibration software scheme. The use of the auto-correction software scheme allows correction of the time base linearity so that the already low 1.5 ps rms timing jitter A flicker or fluctuation in a transmission signal or display image. The term is used in several ways, but it always refers to some offset of time and space from the norm. For example, in a network transmission, jitter would be a bit arriving either ahead or behind a standard clock cycle predominates, as contrasted to the best commercial digital oscilloscopes with linearity errors of 8 ps or greater. Consequently, the measurement of repetitive, short transition-duration ([less than]100 ps) voltage steps is now possible for determining the waveform parameters of precision step generators. The details of this design have been described in a recent paper by NIST scientists entitled, "Improved Time-Base for Waveform Parameter Estimation" given at the Instrumentation and Measurement Technology Conference 2000 held in Baltimor e last May. |
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